1. Field of the Invention
The present invention relates to an integrated structure for a microelectromechanical system (MEMS) device and a semiconductor device and a method of fabricating such integrated structure for a MEMS device and a semiconductor device.
2. Description of the Prior Art
MEMS devices include micromachines integrated with electronic microcircuits on substrates. Such devices may form, for example, microsensors or microactuators which operate based on, for example, electromagnetic, electrostrictive, thermoelectric, piezoelectric, or piezoresistive effects. MEMS devices have been formed on insulators or other substrates using micro-electronic techniques such as photolithography, vapor deposition, and etching. Recently, MEMS is fabricated using the same types of steps (such as the deposition of layers of material and the selective removal of the layers of material) that are used to fabricate conventional analog and digital complementary metal oxide semiconductor (CMOS) circuits.
Additional equipments are not needed if the mass production of the MEMS elements uses the techniques for production of the CMOS devices. The materials generally used for production of the CMOS devices are also can be used. However, the MEMS production has its peculiarity that causes certain problems and difficulties to integrate the semiconductor device production. For example, a release process by means of wet etching is used to make some MEMS components. A sacrificed silicon oxide layer is dissolved by, for example, an HF (hydrogen fluoride) etchant during the release process, and then the MEMS components are separated from each other in thus formed vacant space. Nevertheless, the dielectric layer adjacent to the sacrificed silicon oxide layer and having the semiconductor device therein tends to be damaged during such process. An alternative way to perform the release process is to use HF gas, while water vapor is still needed to activate the release process. In the conventional processes, the release process performed by either wet etching or vapor etching brings lateral damage to the dielectric layer of the CMOS device.
Accordingly, a novel integrated structure for a MEMS device and a semiconductor device and a method of fabricating the same is still needed to allow the MEMS device fabrication to be compatible with the CMOS device fabrication.